Motorola CDM1250 Service Manual

Troubleshooting Flow Chart for Synthesizer Section 12: 3-5
6881091C63-F
3.0 Troubleshooting Flow Chart for Synthesizer
5V
at pin 6 of
D4201
Is
information
from µP U0101
correct
?
Is
U4201 Pin 47
at = 13VDC
?
Is
U4301 Pin 19
<40 mVDC in RX &
>4.5 VDC in TX?
(at VCO section)
?
Start
Visual
check of the
Board
OK?
Correct
Problem
Check 5V
Regulator
U4211
+5V
at U4201
Pins
13 & 30
?
Is
16.8MHz
Signal at U4201
Pin 19
?
Check
Y4261 / Y4262 and
associated parts
Are
signals
at Pins 14 &15
of U4201
?
Check
R4201
Check C4381
Is
U4201
Pin 2 >4.5 VDC in
Tx & <40 mVDC
in Rx
?
Replace
U4201
Remove
Shorts
Is
there a short
between Pin 47 and
Pins 14 & 15 of
U4201
?
Replace or
resolder
necessary
components
Is
RF level at
U4201 Pin 32
-12 < x <-25
dBm
?
Are
R4221,R4222,
R4223,C4221,
C4222 & C4223
OK?
Replace
U4201
If L4225, C4229 & C4227
are OK, then see VCO
troubleshooting chart
Are
Waveforms
at Pins 14 & 15
triangular
?
Do
Pins 7,8 & 9
of U4201 toggle
when channel is
changed?
Check programming
lines between
U0101 and U4201
Pins 7, 8 & 9
Replace
U4201
Check µP U0101
Troubleshooting
Chart
NO
YES
NO
YES
NO
YES
NO
NO
NO
YES
YES
NO
YES
YES
NO
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
YES
Check D4201,
C4202, C4203, &
C4206
5V
at U4201
pins 5, 20, 34
& 36
Ch e c k 5 V
Regulator
U4211
Is
16.8MHz
signal at
U4201 Pin
23?
Replace
U4201
YES
NO
NO
YES
NO
YES

Motorola CDM1250 Specifications

General

Display	Alphanumeric
IP Rating	IP54
Frequency Range	VHF: 136-174 MHz, UHF: 403-470 MHz
Signaling	PL, DPL, MDC1200, Quick Call II
Operating Temperature	-22°F to +140°F (-30°C to +60°C)
Power Output	VHF: 1-25W; UHF: 1-25W